Gmail does allow you to add your account to Outlook without setting up two-factor authentication and using an app password, but you must turn on a setting that allows 'less secure apps' to connect to your account. Select your provider in the drop-down for instructions. The steps to obtain an app password are different for each email provider. Please sign in using your application password.
One way you'll know you need an app password is if you see the following message: 2-factor authentication is set up for your account. This is a different password than your regular email account password. To add your email account to Outlook, you’ll need an app password, also known as an application password. Gmail, Yahoo, iCloud, , and AOL accounts all use two-factor authentication to help verify that you’re the person trying to access your email account. If Outlook won’t accept your password and you know you’re using the password for your email account, you might have an email account that requires additional security. If prompted, enter your password again, then select OK > Finish to start using your email account in Outlook. Enter your name, email address, and password, and click Next.